Hong Hak-soon has been making Tokki book in Tokki language since 1998. The Tokki language (Tokki code) was developed to record a Circle world. (Tokki "토끼" means rabbit in Korean.) As of 2022, the book has nine chapters on 10,000 pages. The circle world is connected to the human world. The two worlds send and receive signals. In the middle, Wink Tokki winked and connected the signal. There are various stories between the two worlds, including Deer Forest, Squirrel World, and Space Clock. He presented his work with paintings, animations, films and NFT ART.